Supported Ionic Liquid Membranes for Removal of Dioxins from High-Temperature Vapor Streams

摘要

Dioxins and dioxin-like chemicals are predominantly produced by thermal processes such as incineration and combustion at concentrations in 1 the range of 10-100 ng of l-TEQ/kg (I-TEQ= international toxic equivalents). In this work, a new approach' for the removal of dtaxms Jrom high-temperature vapor streams using facilitated supported tonic liquid membranes (SILMs) is proposed. The use of ceramic membranes containing speckle ionic liquids, with extremely low volatility, for dioxin removal from incineration sources is proposed owing to their stability at very high temperatures. Supported liquid membranes were prepared by successfully immobilizing the ionic Squids tri-C_8-C_10-alkylmethylammonium dkyanamide ([Aliquat][DCA]) and 1-h-oc-tyt-3-methylimidazolium dicyanamide ([Omim][DCA]) inside the porous structure of ceramic membranes. The porous inorganic membranes tested were made of titanium oxide (TiO_2), with a nominal pore size of 30 run, and aluminum oxide (A1_2O_3), with a nominal pore size of 100 am. The ionic liquids were characterized, and the membrane performance was assessed for the removal of dioxins. Different materials (membrane pore size, type of ionic liquid, and dioxin) and different operating conditions (temperature and flow rate) were tested to evaluate the efficiency of SILMs for dioxin removal. All membranes prepared were stable at temperatures up to 200 ℃. Experiments with model incineration gas were also carried out, and the results obtained validate the potential of using ceramic membranes with immobilized ionic liquids for the removal of dioxins from high-temperature vapor sources.